Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/greatsumini/cc-system/subagent-creatornpx skills add greatSumini/cc-system --skill subagent-creatorgit clone --depth 1 https://github.com/greatSumini/cc-systemWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00049 | $0.00924 |
| Opus 5 | $0.00024 | $0.00462 |
| Sonnet 5 | $0.00010 | $0.00185 |
| Haiku 4.5 | $0.00005 | $0.00092 |
Grade A, and why
subagent-creator scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 128 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Sub-agent Creator
Create specialized AI sub-agents for Claude Code that handle specific tasks with customized prompts and tool access.
Sub-agent File Format
Sub-agents are Markdown files with YAML frontmatter stored in:
- Project:
.claude/agents/(higher priority) - User:
~/.claude/agents/(lower priority)
Structure
---
name: subagent-name
description: When to use this subagent (include "use proactively" for auto-delegation)
tools: Tool1, Tool2, Tool3 # Optional - inherits all if omitted
model: sonnet # Optional - sonnet/opus/haiku/inherit
permissionMode: default # Optional - default/acceptEdits/bypassPermissions/plan
skills: skill1, skill2 # Optional - auto-load skills
---
System prompt goes here. Define role, responsibilities, and behavior.
Configuration Fields
| Field | Required | Description |
|---|---|---|
name |
Yes | Lowercase with hyphens |
description |
Yes | Purpose and when to use (key for auto-delegation) |
tools |
No | Comma-separated tool list (omit to inherit all) |
model |
No | sonnet, opus, haiku, or inherit |
permissionMode |
No | default, acceptEdits, bypassPermissions, plan |
skills |
No | Skills to auto-load |
Creation Workflow
- Gather requirements: Ask about the sub-agent's purpose, when to use it, and required capabilities
- Choose scope: Project (
.claude/agents/) or user (~/.claude/agents/) - Define configuration: Name, description, tools, model
- Write system prompt: Clear role, responsibilities, and output format
- Create file: Write the
.mdfile to the appropriate location
Writing Effective Sub-agents
Description Best Practices
The description field is critical for automatic delegation:
# Good - specific triggers
description: Expert code reviewer. Use PROACTIVELY after writing or modifying code.
# Good - clear use cases
description: Debugging specialist for errors, test failures, and unexpected behavior.
# Bad - too vague
description: Helps with code
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- yesterday First seen · 128 lines · 49 tokens per session scan A 533aae961067
subagent-creator is a skill published in the GitHub repository greatSumini/cc-system (436 stars, last pushed 2mo ago), licensed MIT. It adds 49 tokens to every session and 924 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other skills, from other repositories
weekly-digests
Generate a serial week-by-week narrative digest of a project's full claude-mem timeline. Splits the timeline into per-ISO-week files, then runs one consecutive subagent per week — each receiving the prior week's carry-forward block — to produce one chapter per ISO week of data. Use when asked for "weekly digests"…
agentmail
Use when an agent needs AgentMail CLI email inboxes.
skill-template
Template for creating new Agent Skills for context engineering. Use this template when adding new skills to the collection.
Agent Development
This skill should be used when the user asks to "create an agent", "add an agent", "write a subagent", "agent frontmatter", "when to use description", "agent examples", "agent tools", "agent colors", "autonomous agent", or needs guidance on agent structure, system prompts, triggering conditions, or agent development…
skill-creator
Scaffold a new yoyo skill when a human or community issue asks for one ("add a skill for X", "create a skill that does Y"). Generates correct frontmatter, validates, writes to disk.
subagent-delegation
Canonical protocol for delegating GSD work to native Antigravity subagents — when to delegate, how to invoke, workspace isolation modes, and the inline fallback for older IDE versions.